Study on Microstructure and Tribological Properties of Nano/Micron NbC/In625 Composite Coatings by Laser Cladding

In this study, micron, nano, and nano/micron NbC ceramic‐reinforced In625 alloy coatings are prepared by laser cladding technology, where the effects of different particle sizes of NbC on the coating phase compositions, microstructures, and wear‐resistant properties are systematically investigated. It is shown that all of the additions of NbC with different particle sizes are capable of promoting NbC, Cr23C6, and Laves phases to precipitate in the coatings. They significantly refine the grain organization by hindering the movement of grain boundaries and promoting the pinning effect of grain boundaries, so as to effectively improve the microhardness and wear‐resistant properties of the composite coating. Among them, nano NbC particles have a smaller size, which makes them easier to melt under the irradiation of a high‐energy laser beam, and the distribution of decomposed elements is more homogeneous, so that their refining effect on the coating is better. However, when nano and micron particles are mixed, they produce a synergistic reinforcement mechanism which makes the grain refinement effect of the nano/micron NbC mixed particles better than that of the pure nano NbC. In the performance tests, nano/micron NbC/In625 composite coatings also show the most optimal levels in terms of microhardness and wear resistance.